A potential candidate vaccine for Middle East respiratory syndrome coronavirus (MERS-CoV) is described online in Nature Communications. The vaccine candidate has shown success in producing immunity in mice and macaques against the JordanN3 strain of the virus.

MERS-CoV was first discovered in 2012 and since then between 1118 and 1142 cases and 423 to 465 deaths have been attributed to the virus. Little is known about how MERS-CoV is transmitted and an animal reservoir is suspected but not confirmed. There is currently no cure for the severe respiratory disease that the virus causes in humans.

Wing-Pui Kong, Barney Graham and colleagues now report that inoculating animals with DNA encoding one of the viral proteins and a truncated viral protein can elicit the production of a range of neutralising antibodies in the blood of mice and macaques. Immunization of the macaques conferred protection against MERS-CoV-induced pneumonia. This immunization strategy is the first to induce MERS-CoV neutralizing antibodies that target multiple structures, both inside and outside the virus, which may reduce the ability of the virus to avoid future detection by the immune system through mutation.

This is also the first time that this type of vaccine has been tested in an animal model of MERS-CoV and the first time any potential vaccine has demonstrated protection in non-human primates. However, it is important to note that MERS-CoV infection in primates shows significantly milder disease progression than in humans so it is therefore unclear if the vaccine will be capable of protecting people from the symptoms associated with much more severe disease. More research is also needed to determine the safety and efficacy of this vaccine in humans.